Actually that seems really messy. Is it possible to disable viewing the animal's inventory, instead making an activator with the option to take it's head + dispose of corpse (for example), which in turn disables the animal so it's no longer there?
(I can do activate scripts, and disable scripts)
It seems like disabling the animal's inventory and placing the activator would be easy IF you have your own script running on the animal.
With what I know (meaning, there's a LOT I still need to learn) about the CK, this is how I would do it:
1. Create an alias in the quest
2. Attach a script to that alias and create your OnDeath event - now you can do whatever you want and use the http://www.creationkit.com/BlockActivation_-_ObjectReference if needed.
3. When hunting, force the animal target in to the alias.
Another way to do it, with less coding, would be to simply add the "head" to the animal's (actor) death item. If you don't want to modify each actor in the CK, then probably would use the alias and add the item on death. (As a player, I would expect to activate the corpse as normal and find the head as an item, but I don't know the full context of your mod.)